Stator structure for dynamoelectric machines



March 28, 1939, v w D RQCKER 2,151,955

STATOR STRUCTURE FOR DYNAMO-ELECTRIC MACHINES Filed June 3 1937 INVENTOR WZZM/I/ 0. C/IWZAZ'A ATTORNEY.

Patented Mar. 28, 1939 PATENT OFFICE STATO-R STRUCTURE FOR. nYNAMonmc'rmc MACHINES William D. Cracker, Springfield, Mass, assignor to American Bosch Corporation, Springfield, Mass, a corporation of New York Application June 3, 1937, Serial No. 146,143

2 Claims.

This invention relates to dynamo electric machines such as a magneto having a coil or coils mounted upon a core forming a part of a stationary magnetic circuit or the stator of the machine. The invention resides more particularly in the means for fastening the coil cores in place so that they may be readily inserted in or detached from the remaining stator structure without requiring fastening means altering the magnetic circuit.

In devices of this type as heretofore constructed, it has been common practice to attach the coil cores by screws, with or without clamps, extending through the laminated structure. Such a construction interferes with the magnetic properties of the laminated structure and furthermore such screws may become loose in the course of prolonged use, permitting small air gaps to arise between the core and the pole pieces upon vibration of the machine, thus reducing its efficiency in operation.

It is a primary object of this invention to obviate the above mentioned defects and provide a structure in which the coil core and pole pieces are free from fastening screws and in which the coil core will always be held in intimate contact with the pole pieces.

It is a further object of this invention to provide a structure in which the coil core is resiliently held in proper position in the magnetic circuit and maintained in such position in a manner which will prevent material air gaps arising in the magnetic circuit, while at the same time permitting ready attachment and detachment of the coil.

The above and other objects and features of the invention will be more apparent to those skilled in the art from a consideration of the following detailed description taken in conjunction with the accompanying drawing, in which:

Fig. 1 shows a section through a coil core housing having a coil core mounted in accordance with the present invention; Fig. 2 is a view similar to Fig. 1 but showing a modified form of the coreholding means; Fig. 3 shows a further form of core-holding means; and Fig. 4 illustrates the invention as applied to a magnet rotor type of magneto.

Referring to Fig. 1, reference numeral I indicates a housing of non-magnetic material, as aluminum, in which are cast as inserts a pair of laminated steel poles forming a part of a magnetic circuit of a dynamo electric machine. A coil cover 3 of non-magnetic material, as brass, has the form of a cup with a peripheral flange 4 for attachment to the housing 1 by screws 5. Within the cover 3 is a coil 6, as for instance a magnetizing coil, mounted upon a laminated steel core 1, the end portions of which contact edge- Wlse with suitable integral extensions of the pole 5 piece 2. A pair of flat or strip springs 8, of brass or steel as desired, are attached to the inner surface of the cover 3 by rivets 9 so that their free ends bear upon the core I on opposite sides of the coil 16 and press the core firmly against the pole 10 pieces 2 to maintain good magnetic contact therewith at all times during operation of the machine. Freedom from bolts or other similar fastening means extending through the coil core and into the pole pieces is thus provided, while 15 ease of attachment or detachment of the coil and core from the remaining structure is assured. It is obvious that the two springs 8 may be replaced by a single plate spring in which case it should be of non-magnetic material.

The form shown in Fig. 2 is similar in all respects to that shown in Fig. 1 except that a pair of coil springs 9 of steel or brass are used to hold the coil core in proper position. This form is desirable where stronger springs are necessary 25 to maintain a heavier coil in. proper magnetic contact.

It will be noted that in the forms of Figs. 1 and 2, the coil cores 1 are held against longitudinal displacement by contact at each end with the inside of the cover 3. Where it is desired to maintain a suitable clearance between the ends of the coil core and the side walls of the cover, the form shown in Fig. 3 may be used. In this form thefree ends of the flat springs Ii! are bent to hold the core against longitudinal displacement as well as lateral displacement.

Fig. 4 illustrates the application of the invention to a magneto ,having an ignition coil ll of the usual primary and secondary windings on the core 12, and a magnet rotor 13. In this case the coil is in a horizontal position so that its weight aids rather than opposes the action of the springs I4. These springs may be of heavy steel or brass, the cover l5 being provided with sockets 16 for retaining the springs in proper position and to promote the ease of assembly of the magneto.

Having thus described the invention, what is claimed is:-

1. In a rotatable dynamo electric machine, a coil, a laminated core for said coil forming a part of the magnetic circuit of the stator of said machine and having ends projecting from each end of said coil, a non-magnetic metal housing, laminated polepieces fixed in said housing cooperating with the projecting ends of said core, a cover for said coil and core detachably mounted upon said housing, resilient means compressed between said cover and core for forcing said core into contact with said polepieces, whereby said coil and core are freely removable from said machine upon detachment of said cover, and a rotor completing the magnetic circuit of said stator.

2. In a rotatable dynamo electric machine, a coil, a laminated core for said coil forming a part of the magnetic circuit of the stator of said machine and having ends projecting from each end a rotor completing the magnetic circuit of said 10 stator.

WILLIAM D. CROCKER. 

